Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a main shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Energy storage devices (ESDs) are often used in wind and solar farms to fulfill a specific use case. ESDs could be batteries, supercapacitors, pumped storage, compressed gas storage, flywheels, and/or any other device in which, or means by which energy can be stored for later use. A typical use case for ESDs in a wind farm is to store the energy produced by the wind turbines when the wind farm is curtailed by the grid operator and to release and sell the energy when the curtailment is lifted. Oftentimes, the timing of such curtailment events is not predictable by the wind farm operators. This unpredictability necessitates that the ESDs be kept at a very low state of charge (SOC) in anticipation of a curtailment event.
ESDs can also be used to supply the energy consumed by the auxiliary loads and losses inside the wind farm. Auxiliary loads represent the energy consumed by the devices inside the wind turbine such as yaw motors, various pumps, and heaters. Auxiliary losses represent the energy consumed by the no-load losses in the cables and the transformers in the wind farm. When the wind farm is producing power, the energy output of the wind farm to the grid is net of the above auxiliary loads and losses. When the wind speeds are low and the wind farm is not generating power, the wind farm consumes energy from the grid to feed the auxiliary loads and losses. Oftentimes, the energy rates that the wind farm operator pays for the energy consumed from the grid can be several times the energy rates the operator gets paid for the energy produced and supplied to the grid. Thus, the ESDs can be used to store energy at a low cost when the wind farm is producing power and to use that energy to supply the auxiliary loads and losses when the farm is not producing, thus offsetting the high cost of energy consumed.
However, the curtailment use case requires the ESDs to be kept at a low SOC in anticipation of an unpredictable curtailment event, whereas the auxiliary loads/losses use case requires the ESDs to be kept at a relatively high SOC in anticipation of drop in wind speeds that would result in the wind farm transitioning from producing to consuming energy.
In view of the aforementioned issues, it is desirable to provide a system and method to appropriate the ESD(s) for both use cases.